Have just updated from Mojave to Monterey. I was able to successfully install KiCad6 along side KiCad5. Both use a parent folder named just “KiCad”. So, before the install, I renamed the parent folder of the old version to be “KiCad5”. I then let the new install folder remain “KiCad” to avoid any update problems. So far, this seems to be working well.
Oregon Research Electronics